Modens

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MODEMS

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INTRODUCCION........................................................................................................................................... 4 1.1 HISTORIA DE LOS MODEMS ............................................................................................................. 4 1.2 DEFINICION.......................................................................................................................................... 5 CONCEPTOS GENERALES ......................................................................................................................... 5 2.1 LINEAS A 2 ó 4 HILOS ......................................................................................................................... 52.2 LINEAS DEDICADAS Y CONMUTADAS.......................................................................................... 5 2.3 SIMPLEX, HALF-DUPLEX, FULL_DUPLEX..................................................................................... 6 2.4 MODEMS SINCRONICOS Y ASINCRONICOS.................................................................................. 6 2.5MODULACION...................................................................................................................................... 7 2.5.1 MODEMS FSK ............................................................................................................................... 7 2.5.2 MODEMS PSK............................................................................................................................... 7 2.5.3 MODEMS QAM ............................................................................................................................. 7 2.6 DEMODULACION ................................................................................................................................ 7 2.6.1 Comparación entre detección sincrónica y detecciónno-coherente:............................................. 10 2.6.2 Demodulación muestreada ............................................................................................................ 11 2.7 SEUDO ALEATORIZACION (Scrambling)........................................................................................ 11 2.8 TECNICAS DE ECUALIZACION...................................................................................................... 12 NORMALIZACION y PROTOCOLOS ....................................................................................................... 12 3.1 Modems V.16 ........................................................................................................................................ 13 3.2 Modems V.19........................................................................................................................................ 13 3.3 Modems V.20 ........................................................................................................................................ 13 3.4 Modems V.21 ........................................................................................................................................ 133.5 Modem V.22.......................................................................................................................................... 14 3.6 Modems V.22 bis .................................................................................................................................. 14 3.7 Modems V.23........................................................................................................................................ 16 3.8 Modems V.26 ........................................................................................................................................ 17 3.9 Modems V.26 bis .................................................................................................................................. 17 3.10 Modems V.26 ter...